97L gets disrupted by Hispaniola

By: Dr. Jeff Masters , 12:53 PM GMT on July 21, 2010

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A tropical wave (Invest 97L) near the north coast of Hispaniola has been disrupted by interaction with the island, plus the effects of moderate wind shear of 10 - 20 knots. The storm is no longer a threat to develop into a tropical depression today, and the Hurricane Hunter flight that was scheduled for today has been postponed until Thursday. The disturbance has brought heavy rains of 8+ inches to Culebra, Vieques, the Virgin Islands, and some of the northern Lesser Antilles Islands. Wunderblogger Weather456 reported that the power was knocked out on the island of St. Kitts for about 24 hours, due to the intense lightning associated with 97L. All of Puerto Rico and the Virgin Islands are under flash flood watches today.

Satellite images of 97L show a relatively meager number of heavy thunderstorms that are not well-organized. The curved bands to the north and east of the center have disappeared, and there is no evidence of low-level spiral banding or of a surface circulation. Surface observations over the northern Dominican Republic show only light winds, with no westerly winds indicating that a surface circulation is forming. Long-range radar loops from San Juan show a much reduced amount of thunderstorm activity.


Figure 1. Total radar-estimate rainfall for 97L.

Track Forecast for 97L
The storm is in a fairly straightforward steering current environment, and 97L should progress steadily to the west-northwest through Saturday. The rains from 97L's thunderstorms will bring the threat of isolated flooding to the Dominican Republic today, and to Haiti on today and Thursday. Heavy rains from 97L will affect eastern Cuba, the Turks and Caicos Islands, and the eastern Bahamas Thursday, and South and Central Florida can expect heavy rains to arrive Thursday night or Friday morning. The latest suite of model runs from 2am EDT this morning (6Z) foresee 97L making landfall on the Florida coast somewhere between Miami and Cape Canaveral on Friday, then continuing into the Gulf of Mexico on Saturday. Only the Canadian model foresees a threat to Texas, and the other models predict a second landfall between eastern Louisiana and the Florida Panhandle.

Intensity Forecast for 97L
The primary detriment to development of 97L today will be its close proximity to the landmass of Hispaniola. Once the storm pulls away from the island tonight, 97L has a better chance of development. Also hindering development over the next two days will be the presence of dry, stable air in its path over the Bahamas, thanks to the upper-level low to the north of the Dominican Republic. The SHIPS model predicts shear will stay in the moderate range, 10 - 20 knots, over the next three days, which should allow for some steady development of 97L on Thursday and Friday before it reaches Florida. NHC is giving 97L a 60% chance of developing into a tropical depression by Friday, which is a reasonable forecast. I think there is a 70% chance 97L will eventually become Tropical Storm Bonnie, sometime in the next five days. Sudden rapid development before 97L reaches Florida is unlikely, due to the storm's current state of disorganization and the dry air over the Bahamas. It's very unlikely that 97L has time to organize into a hurricane before hitting Florida. I put the odds of 97L making it to hurricane strength before reaching Florida at 5%, and I give a 20% chance it will be a hurricane in the Gulf of Mexico. The probability of 97L being a hurricane in the Gulf of Mexico will depend heavily upon how long the storm spends over water in the Gulf, which is very uncertain. The environment in the Gulf of Mexico should be favorable for intensification, if passage over Florida does not disrupt the storm too much.

I'll have a new post Thursday morning, or earlier if there's a major change to 97L.

Famed climate scientist Steven Schneider dies
Steven Schneider, one of the most influential and talented climate scientists of our time, died on Monday. Ricky Rood has a tribute to Dr. Schneider in today's blog. Ricky comments, "He is known for feistiness. His last book was Science as a Contact Sport: Inside the Battle to Save Earth's Climate. He was a man who was, bluntly, harassed and threatened by those who did not like his message. He never shrank from the battle."

Jeff Masters

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Quoting atmosweather:


None of the global models show that scenario, but some of the local models have persisted with a more N-ern track for a couple of days. But even the NAM still shows the system traveling across S FL, and that's the most northern of the reliable models right now.


Ok. Thanks didn't think I'd seen one that north.
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Sigh! Lake Charles. No help at all and seems to know less than we do.

THE HIGHEST RAIN CHANCES ARE EXPECTED SUNDAY AND MONDAY TIMEFRAME.
THIS IS IN RESPECT TO THE TROPICAL WAVE THAT HAS BEEN MAKING
HEADLINES NEAR HISPANIOLA THIS WEEK. PER NHC TROPICAL WEATHER
OUTLOOK...THIS SYSTEM STILL HAS A 40 PERCENT OF DEVELOPMENT INTO A
TROPICAL CYCLONE WITHIN THE NEXT 48 HOURS. HOWEVER...OUR CURRENT
THINKING IS THE LOCAL IMPACT WILL BE MAINLY ENHANCED RAIN CHANCES.
WIND SHEAR FROM THE UPPER LEVEL LOW NEAR SOUTH FLORIDA IS CURRENTLY
HINDERING DEVELOPMENT OF THIS SYSTEM...AND THAT MAY HOLD TRUE AS
IT MOVES WEST-NORTHWEST ACROSS THE GULF THIS WEEKEND.
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Quoting homelesswanderer:
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
403 AM EDT THU JUL 22 2010 Link

FRIDAY THROUGH SATURDAY...THE MODELS SHOW THE TROPICAL WAVE
CURRENTLY OVER THE BAHAMAS CONTINUING ON ITS NORTHWEST TRACK ACROSS
THE CENTRAL FLORIDA PENINSULA AND OUT OVER THE EASTERN GULF OF
MEXICO BY SATURDAY AFTERNOON.
ALTHOUGH THERE ARE SOME UNCERTAINTIES
WITH REGARD TO THE DEVELOPMENT OF THIS SYSTEM AT THIS
TIME...INCREASING MOISTURE AND RAIN CHANCES APPEAR LIKELY THROUGH
THIS PERIOD AS THIS FEATURE PASSES SOUTH OF THE AREA
SATURDAY.

HUH?? Do any models show that?


None of the global models show that scenario, but some of the local models have persisted with a more N-ern track for a couple of days. But even the NAM still shows the system traveling across S FL, and that's the most northern of the reliable models right now.
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3859. xcool
homelesswanderer .I HAVE NO CLUE
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AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
403 AM EDT THU JUL 22 2010 Link

FRIDAY THROUGH SATURDAY...THE MODELS SHOW THE TROPICAL WAVE
CURRENTLY OVER THE BAHAMAS CONTINUING ON ITS NORTHWEST TRACK ACROSS
THE CENTRAL FLORIDA PENINSULA AND OUT OVER THE EASTERN GULF OF
MEXICO BY SATURDAY AFTERNOON.
ALTHOUGH THERE ARE SOME UNCERTAINTIES
WITH REGARD TO THE DEVELOPMENT OF THIS SYSTEM AT THIS
TIME...INCREASING MOISTURE AND RAIN CHANCES APPEAR LIKELY THROUGH
THIS PERIOD AS THIS FEATURE PASSES SOUTH OF THE AREA
SATURDAY.

HUH?? Do any models show that?
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3856. xcool


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3855. xcool



97L MOVE CLOSE TO fL

98L

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Station 41046
NDBC
Location: 23.836N 70.863W
Conditions as of:
Thu, 22 Jul 2010 07:50:00 UTC
Winds: E (80°) at 21.4 kt gusting to 25.3 kt
Significant Wave Height: 9.2 ft
Dominant Wave Period: 9 sec
Mean Wave Direction: E (95°)
Atmospheric Pressure: 29.95 in and falling
Air Temperature: 77.9 F
Dew Point: 72.7 F
Water Temperature: 83.7 F
View Details - View History

Bouy report from station in E. Bahamas
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3852. xcool
HA
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Quoting xcool:
WHERE ROB ?


I dunno. Maybe sleeping. He was cheating on us with the day crew. HMPH! LOL!
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Quoting TX2FL:
So is South Florida as in Broward on North out of the woods on 97L now?


You are never out of the woods or clear until there is no longer a storm
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3848. xcool
WHERE ROB ?
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3847. xcool
;)!!!
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Quoting atmosweather:


Well we will have to watch the evolution of the model runs with regards to the strength of the SE U.S. ridge and the placement of that ULL. As of now I don't see any troughs that could come through the Plains region and erode the W-ern part of the ridge...so the ULL would be the only feature able to turn the system NW or NNW. Otherwise, it will track WNW-ward virtually all the way to the coast, which would put N TX in the crosshairs. But there is still a lot of time to go. All of LA and TX needs to watch this carefully. FL is going to be fortunate this time around.


Ok. Thanks. :)
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Just to confuse me more... :)

ARINE WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
200 AM EDT THU JUL 22 2010

MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA
AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W.

GULF OF MEXICO 1010 MB SURFACE LOW CURRENTLY CENTERED NEAR
21N94W WILL DRIFT TO THE W AND COULD POSSIBLY BECOME A TROPICAL
CYCLONE WITHIN THE NEXT 48 HOURS. SCATTERED TO NUMEROUS SHOWERS
AND TSTMS ARE WITHIN 180 NM NE OF THE LOW. RIDGE FROM NORTHERN
FLORIDA TO LOUISIANA WILL PERSIST THROUGH FRI. E-SE WINDS 15-20
KT ARE BLOWING ACROSS THE STRAITS OF FLORIDA AND THE EASTERN
GULF MAINLY S OF 26N E OF 88W. WINDS WILL DECREASE ACROSS THE
STRAITS OF FLORIDA LATER TODAY AND TONIGHT BUT COULD INCREASE
AGAIN AS A TROUGH OR A LOW PRES MOVES ACROSS THE BAHAMAS TOWARD
S FLORIDA FRI. THE LOW AND TROUGH ARE FORECAST TO MOVE INTO THE
NE GULF FRI EVENING AND INTO THE NORTHERN MIDDLE GULF SAT
EVENING.

Link
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Quoting homelesswanderer:


Yuck that looks like it drags right to TX/LA


Well we will have to watch the evolution of the model runs with regards to the strength of the SE U.S. ridge and the placement of that ULL. As of now I don't see any troughs that could come through the Plains region and erode the W-ern part of the ridge...so the ULL would be the only feature able to turn the system NW or NNW. Otherwise, it will track WNW-ward virtually all the way to the coast, which would put N TX in the crosshairs. But there is still a lot of time to go. And remember, the ULL is the same one that has been inhibiting development throughout this week, so it will be key to the potential strength of 97L all the way through its life. All of LA and TX needs to watch this carefully. FL is going to be fortunate this time around.
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3843. xcool
HMM
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Quoting atmosweather:


There is a possibility of a turn to the NW or NNW once it passes through the central GOM because of a ULL that may be near NW TX, which would push the system on a slightly more northerly path around the periphery of the SE U.S. ridge. You can see the ULL on the GFS 84 hr forecast (top right)


Yuck that looks like it drags right to TX/LA
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Quoting TX2FL:
Thanks..now it looks like it may hit Texas, I remember someone saying yesterday that a low was going to block it from Texas coast.


There is a possibility of a turn to the NW or NNW once it passes through the central GOM because of the ULL that may be near NW TX, which would push the system on a slightly more northerly path around the periphery of the SE U.S. ridge. You can see the ULL on the GFS 84 hr forecast (top right)
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3840. xcool
canehater1 8


WOW 31K
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3838. TX2FL
Thanks..now it looks like it may hit Texas, I remember someone saying yesterday that a low was going to block it from Texas coast.
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42055
NDBC
Location: 22.017N 94.046W
Conditions as of:
Thu, 22 Jul 2010 06:50:00 UTC
Winds: E (90°) at 19.4 kt gusting to 31.1 kt
Significant Wave Height: 6.2 ft
Dominant Wave Period: 7 sec
Mean Wave Direction: E (94°)
Atmospheric Pressure: 29.85 in and falling
Air Temperature: 82.8 F
Dew Point: 76.8 F
Water Temperature: 83.5 F
Wx buoy closest to 98-L
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3836. xcool
Everything is up in the air right NOW
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Quoting TX2FL:
So is South Florida as in Broward on North out of the woods on 97L now?


Very likely. The models have been slow to shift SW-ward because they don't perform well with undeveloped systems. The synoptic pattern in this case is pretty straightforward and will not change significantly. The deep layer ridge over the SE will push 97L basically WNW through the next 4-5 days.
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Quoting TX2FL:
So is South Florida as in Broward on North out of the woods on 97L now?


I wouldn't say so yet. That model run is too close to Fl and might change.
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Quoting atmosweather:


Well I was here everyday during 2005 as were many people that still post here. It was indescribable. And that was with much much less overall posters.


I can imagine! I couldn't keep up today.
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3832. xcool
IMO "I Can See 97L Get up to' 65K
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Quoting xcool:


SHE hungry NOW I NEED FOOD

UPDATE


What a difference a few hours make.
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Quoting homelesswanderer:


I agree. Could you imagine this blog with 3 or 4 storms lined up. Lol. Its chaos now.


Well I was here everyday during 2005 as were many people that still post here. It was indescribable. And that was with much much less overall posters.
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3829. TX2FL
So is South Florida as in Broward on North out of the woods on 97L now?
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Why did the EURO pick now of all times not to update their run. On the close up models. Sigh
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Quoting washingaway:
If the ULL gets far enough west of 97L, it will actually help with the outflow.


Yes. A ULL backing away W-ward from a tropical disturbance is the perfect ventilation system.
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3826. xcool


SHE hungry NOW I NEED FOOD

UPDATE
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Quoting TampaSpin:


97L is ready for take off...i called it wrong today as it had multiple swirls that i thought the one on the East side would take over......that did not happen...just shows how strong the swirl is with the main swirl...until i see a visible....really hard to say what it is doing...but, things are sure starting to become more favorable that is for sure.


The main mid level energy is still lagging around 100 miles behind the current surface reflection so it's still very vertically tilted. The fact that the ULL is exiting at a faster pace is helping provide more outflow and slightly relaxed shear which is why we are seeing some decent organization. You can see where the best upper divergence is, which explains why most of the convection is still E of the center. It won't become a TC until it can actually fire convection over the LLC or the mid level energy catches up.
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Quoting xcool:



BY Met Tech

easternuswx.com/


Nice model. I would only get the outer bands with that. :)
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3823. xcool
TampaSpin ;0
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If the ULL gets far enough west of 97L, it will actually help with the outflow.
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3821. 789
Quoting TampaSpin:
Time to get some ZZZZZZ's......nite everyone!
thanks for your input gn
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3820. xcool



BY Met Tech

easternuswx.com/
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Quoting xcool:
TampaSpin .decreasing shear


Yep the TUTT or ULL whichever one wants to call it is lifting out very fast now......things are changing for 97L...lets see how hungry she might be now with nothing blowing her tops off.
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Quoting atmosweather:


Usually we get one or two of those "storm trains" per busy season...so there's probably going to be one this year too considering the likelihood of a very active season. But it's nothing to worry about for now.


I agree. Could you imagine this blog with 3 or 4 storms lined up. Lol. Its chaos now.
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3817. xcool
homelesswanderer IKNOW.
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Quoting homelesswanderer:


Yeah. That reminds me of the parade of storms in 2008 out there. Hopefully not this year.


Usually we get one or two of those "storm trains" per busy season...so there's probably going to be one this year too considering the likelihood of a very active season. But it's nothing to worry about for now.
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Quoting xcool:
homelesswanderer DAMM I FEEL PLAYER :(


It's all good. Just messin with ya. :)
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Time to get some ZZZZZZ's......nite everyone!
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3813. xcool
TampaSpin .decreasing shear
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Quoting atmosweather:


No need to worry about that...that's more than a week from now...models are useless for that timeframe.


Yeah. That reminds me of the parade of storms in 2008 out there. Hopefully not this year.
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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